Fix pass in stateT and eitherT MonadWriter instances #61

Job	Run time
build (coqorg/coq:8.9)	5m 33s
build (coqorg/coq:8.14)	10m 24s
build (coqorg/coq:8.20)	15m 16s
build (coqorg/coq:8.12-ocaml-4.10-flambda)	6m 27s
build (coqorg/coq:8.18)	10m 38s
build (coqorg/coq:8.11)	5m 0s
build (coqorg/coq:8.15)	10m 56s
build (coqorg/coq:8.16)	10m 28s
build (coqorg/coq:8.13)	4m 52s
build (coqorg/coq:8.17)	10m 28s
build (coqorg/coq:8.19)	30m 15s
build (coqorg/coq:dev)	10s
	2h 0m 27s

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